Background

This chronic fungal infection is now known as Jorge Lobo's disease or lacaziosis. It is caused by the fungus Lacazia loboid (formerly Loboa loboi). The infection is characterized by keloidal nodules occurring on the face, ears, or extremities. Disseminated disease may occur. The lesions usually spare the mucous membranes. The lesions may be pruritic, asymptomatic, or hypoesthetic. Less common presentations include macules, papules, atrophic, and verrucous plaques.

OUTLINE

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/ Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/ Immunohistochemistry/ Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Keloidal blastomycosis, Lobo's disease, Jorge Lobo's disease
GEOGRAPHY	Central and South America

 

PATHOGENESIS	CHARACTERIZATION
Fungus Lacazia loboi (formerly Loboa loboi)	Has never been cultured
Macrophage and TGF-beta immunohistochemical expression in Jorge Lobo's disease. Xavier MB, Libonati RM, Unger D, Oliveira C, Corbett CE, de Brito AC, Quaresma JA. Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém-PA 66055-240, Brazil.	Hum Pathol. 2008 Feb;39(2):269-74. Abstract quote Jorge Lobo's disease, or lacaziosis, is a chronic deep mycosis that clinically manifests as solid, variable-sized nodular parakeloidal lesions. Few studies have characterized the in situ cellular and humoral immune response, especially the involvement of cytokines with immunosuppressive effects such as TGF-beta. The objective this paper was to analyze the expression of TGF-beta in cutaneous lesions in lacaziosis and investigate its importance in the etiopathogy of the disease. The results indicate that the abundance of collagen bands, together with weak immunolabeling for CD68 seen in macrophages, indicates a concomitant effect of TGF-beta inhibiting macrophages and inducing fibrosis, which is responsible for the keloid aspect frequently acquired by these lesions. Finally, the evolution of the infection supports the hypothesis that TGF-beta plays a fundamental role in the etiopathology of Lacazia loboi infection, either by inhibiting the cellular immune response mainly mediated by macrophages or by inducing fibrosis. Further studies are necessary to better characterize the phenotype of the inflammatory infiltrate as well as the participation of other cytokines and growth factors in the tissue response of the host in Jorge Lobo's disease.

 

LABORATORY/ RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
Laboratory Markers
Serology	No serological tests exist

CLINICAL VARIANTS	CHARACTERIZATION
Human case of lobomycosis. Elsayed S, Kuhn SM, Barber D, Church DL, Adams S, Kasper R. Calgary Laboratory Services, Calgary, Alberta, Canada.	Emerg Infect Dis. 2004 Apr;10(4):715-8. Abstract quote   We describe a 42-year-old woman with histologically confirmed lobomycosis, a cutaneous fungal infection rarely reported outside of Latin America. Our case represents the first published report of imported human lobomycosis in Canada and the fifth in an industrialized country.
Report of the first human case of lobomycosis in the United States. Burns RA, Roy JS, Woods C, Padhye AA, Warnock DW. North Georgia Surgical Associates, Dalton, Georgia 30722, USA.	J Clin Microbiol. 2000 Mar;38(3):1283-5. Abstract quote   We describe the first human case of lobomycosis caused by Lacazia loboi in a 42-year-old white male resident of Georgia. The patient had traveled to Venezuela 7 years earlier, where he had planned to rappel down Angel Falls in Canaima. Although he never actually rappelled the falls, he did walk under the falls at least three times, exposing himself to the high water pressures of the falls. He noticed a small pustule with surrounding erythema developing on the skin of his right chest wall. The lesion gradually increased in size and had an appearance of a keloid. For cosmetic reasons, the patient sought medical treatment to remove the lesion. After an uncomplicated excision of the lesion, the patient recovered completely. The excised tissue was fixed in formalin for pathologic examination. Tissue sections stained by hematoxylin and eosin, periodic acid-Schiff stain, and Gomori methenamine silver stain procedures showed numerous histiocytes, multinucleated giant cells, and numerous globose or subglobose, lemon-shaped cells producing multiple blastoconidia connected by narrow tube-like connectors and catenate chains of various lengths characteristic of L. loboi.
Lobomycosis (keloidal blastomycosis): case reports and overview. Fuchs J, Milbradt R, Pecher SA. Zentrum der Dermatologie und Venerologie, Klinikum der Johann Wolfgang Goethe Universitat Frankfurt, West Germany.	Cutis. 1990 Sep;46(3):227-34. Abstract quote   Lobomycosis is a deep fungal disease of the skin without involvement of internal organs or mucous membranes. The disease is characterized by skin nodules and plaques resembling keloid involving the earlobes, distal parts of the upper and lower extremities, and buttocks. In severe cases, large skin areas can be covered by disseminated or grouped and confluent nodules. Most cases are reported from South and Central America. The fungus Paracoccidioides (Glenosporella) loboi is abundant in lesions but is extremely difficult to culture. Lobomycosis is resistant to chemotherapy, but in some cases it can successfully be treated by excision. Although the diagnosis is easily established by its typical clinical, histologic, and microbiological features, it is often misdiagnosed by physicians not familiar with the disease. We describe here five patients and present an overview of this rare disease.

 

HISTOLOGICAL TYPES	CHARACTERIZATION
General	Dense infiltrate with fibrosis in the dermis and subcutaneous tissue Mixed inflammatory cells with multinucleated histiocytes and intracellular asteroid bodies in giant cells Numerous fungi in giant cells and histiocytes characterized by large (6-12 um) homogenous, round to oval thick walled cells with a double contour membrane Budding involving multiple buds appearing as a chain
Vinyl adhesive tape also effective for direct microscopy diagnosis of chromomycosis, lobomycosis, and paracoccidioido-mycosis. Miranda MF, Silva AJ. Dermatology Service, Centro de Ciencias da Saude, Universidade Federal do Para, 66055-240 Belem, Para, Brazil; Hospital da Fundacao Santa Casa de Misericordia do Para, 66050-380 Belem, Para, Brazil.	Diagn Microbiol Infect Dis. 2005 May;52(1):39-43. Abstract quote   Among the existing techniques for direct microscopy diagnosis in mycology, vinyl adhesive tape (VAT) preparations have proved their usefulness for Malassezia spp., Candida spp., and dermatophyte superficial infections. The collection and identification of fungal agents can be performed easily by the VAT technique, as demonstrated in this work, for the setting of some deep-seated cutaneous mycoses, where infectious agents can be observed in the horny layer of the epidermis in transepidermal elimination events. Preliminary results obtained in a series of 19 cases (chromomycosis, 12; lobomycosis, 5; paracoccidioidomycosis, 2) yielded positive results in 17 (89.47%). Failures for proper microscopic diagnosis detection happened in just 2 cases, 1 for chromomycosis and 1 for paracoccidioidomycosis. These results, although encouraging, were obtained from a relatively small patient population sample. Thus, the authors recommend further tests using this direct microscopy technique in a larger number of patients to validate these preliminary results and to explore its sensitivity in cases of small lesions.
ASTEROID BODIES
The asteroid body of lobomycosis. Rodriguez G, Barrera GP. Department of Pathology, School of Medicine, National University, Bogota, Colombia.	Mycopathologia. 1996-97;136(2):71-4. Abstract quote   Lobomycosis is a dermal mycosis produced by Loboa loboi. It gives rise to dermal granulomas in which giant cells phagocytose an overwhelming number of fungi. Intracytoplasmatic asteroid bodies (AB) have been observed in some giant cells. Their nature is unknown and they have been confused with the sporotrichotic AB. We studied 84 skin biopsies from 53 patients with lobomycosis, 7 by electron microscopy (EM). Immunohistochemistry with a polyclonal anti-Sporothrix schenckii antibody was performed in five biopsies. We found AB in the giant cells in 22 of the 84 biopsies on HE staining. They appeared as single eosinophilic intracytoplasmic structures surrounded by a clear empty space. This clear space did not appear when the biopsy was fixed with OSO4, thus indicating that it is lipid in nature, and that the vacuole is an artefact produced by lipid extraction. Under the EM, the AB consist of bundles of dense, filamentous material, dense bodies and myelin structures resembling the image of AB in sarcoidosis. Some giant cells containing AB either phagocytosed only few fungi or did not contain any of them. The AB and the fungi did not react with the anti-sporotrichotic antibody, which stained the extracellular AB of sporotrichosis. These two asteroid structures are, therefore, different and unrelated phenomena.

 

SPECIAL STAINS/ IMMUNOPEROXIDASE	CHARACTERIZATION
Special stains	GMS and PAS stains positive

Macpherson and Pincus. Clinical Diagnosis and Management by Laboratory Methods. Twentyfirst Edition. WB Saunders. 2006.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
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Last Updated February 11, 2008

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